Beck, R&J ELECTRIC ACTUATORS FOR INDUSTRIAL PROCESSCONTROL 11-1_9 用户手册

20

OPERATION

 

Beck electronic control drives have individual 

cast aluminum compartments for each of the 
five main components:  The control motor, wiring 
terminal block, drive train, digital control module, 
and control end.  Gasketed covers and sealed 
shafts make the drives ideally suited to outdoor 
and high humidity environments.
 

Heavy cast mechanical stops built into the 

housing are designed to prevent accidental over-
travel damage during manual cycling, and ensure 
that proper orientation is maintained between 
the output shaft and the feedback system.  Drive 
travel is centered between the mechanical stops 
unless otherwise specified at time of order.

 

The Beck control motor is a synchronous 

inductor motor which operates at a constant 
speed of 72 RPM or 120 RPM in synchronism 
with the line frequency.
 

Motors are able to reach full speed within 25 

milliseconds and stop within 20 milliseconds; 
actual starting and stopping times will vary with 
load.
 

Beck motors have double grease-sealed 

bearings and require no maintenance for the life 
of the motor.

 

The gear train is a four-stage reduction, spur 

gear drive constructed with only heat-treated alloy 
steel and ductile iron gears for durability and long 
life.
 

The drive train consists of the control motor and 

Handwheel, reduction gears, main gear, output 
shaft, and crank arm.  The main gear / output shaft 
and third stage gears are common to all units of 
a particular drive model.  The second and first 
stage gears are part of the field-interchangeable 
gear module.  Different combinations of gear 
modules and drive motors determine the drive’s 
output torque and timing.  See Table 9, page 83 
for details.
 

On all models except the 11-169, the output 

shaft is limited by mechanical stops to 108° of 
rotation.  On model 11-169 drives, the output shaft 
is limited by mechanical stops to 98° of rotation.  
Optional main gear / output shaft assemblies are 
available that permit multi-revolution output rotation.  
Mechanical stops are not included on these models.  
Mechanical transmission of output shaft position to 
the control end is provided by a right angle gear set 
driven directly by the output shaft.

 

An integral part of every control motor is the 

self-locking mechanism.  This mechanical device 
couples the motor to the gear train and transmits 
full motor torque when rotated in either direction.  
When the motor is de-energized, the SLM 
instantaneously locks and holds the output shaft 
in position.

 

Every Beck control drive is furnished with a 

Handwheel to permit manual operation of the valve or 
damper without electrical power.  Its solid construction 
design includes no spokes or projections, and turns at 
a safe, slow speed.  The Handwheel is located at the 
rear of the control motor housing.  The Handwheel is 
coupled directly to the motor shaft and rotates when 
the motor runs.  Manual operation of the Handwheel 
(with electric Handswitch in “STOP” position) turns 
the motor and the rest of the drive train without 
incorporating a clutch.

 

A local electric Handswitch is provided on Beck 

drives to permit operation at the valve or damper, 
independent of the controller.  As a safety feature, 
the Handswitch is designed so that the controller can 
operate the drive only when it is in the “AUTO” position.  
The sequence of the Handswitch is:  “AUTO”, “STOP”, 
“CW”, “STOP”, “CCW”.  When the Handswitch 
is turned fully clockwise, “AUTO” should be 
indicated.  
 

In the “AUTO” position, two contacts are closed 

and the DCM-2 completes the control circuit.
 

In the “CW” or “CCW” positions, contacts are 

closed to operate the drive independently of the 
controller.
 

In the “STOP” position, all contacts remain open.

 

To prevent Handswitch initiated motion,  remove 

the jumper between terminals A and C.  CAUTION:  
AC power to the drive must be turned off before 
removing the jumper.

 

Two over-travel limit switches and up to 

four optional auxiliary switches are provided on 
Beck drives.  Switch cams are clamped onto 
the control shaft which rotates in relation to the 
output shaft.  Cam position is field-adjustable.  
Switches are rated 6 A, 120 V ac.  All auxiliary 
switch connections are made on the terminal 
block.